Reaction Kinetics, Mechanisms and Catalysis最新文献

Synthesizing biogasoline from castor oil was catalyzed by Activated Natural Zeolite (ANZ) catalyst modified Ni and Zn metals in batch-cracking reactor. The process was affected by the modified catalyst on variation of Ni:Zn ratio (1:1, 1:2, and 2:1) at the calcination temperature of 500 °C, and variation of the calcination temperature (500, 600, and 700 °C) At Ni–Zn (1:1). After characterizations and analysis, the higher the calcination temperature, the lower the acidity of the catalyst caused the resulting yield also decreases. The density of the product obtained ranged from 0.765–0.83 g/mL, the viscosity ranged from 1.42–1.95, the refractive index was 1.421–1.431, and the calorific value tested on the cracking product with Ni:Zn (1:1) (500 °C) Fraction I, Fraction II, and Fraction III were 0.9966 kcal/kg, 0.9068 kcal/kg, and 0.8755 kcal/kg, respectively. The results of FTIR and GC–MS showed that the composition of the catalytic cracking product was composed of C₆–C₁₄ hydrocarbons consisting of aldehydes, alkanes, alkenes, and carboxylic acids. The composition was dominated by biogasoline compounds (C₅–C₁₂).

In response to the pressing challenges in various fields, particularly healthcare and infection prevention, this research explores the synthesis, characterization, and assessment of ZnO–Ag nanocomposites for antibacterial properties. Employing a solvothermal method, silver nanoparticles were incorporated into hydrothermally synthesized zinc oxide nanorods, aiming to harness their synergistic antibacterial effects. The research systematically analyses the nanocomposites, unveiling their structural and compositional features. Antibacterial potential is evaluated through agar well diffusion assay, demonstrating increased efficacy against diverse bacteria. With implications extending to biomedical applications, these nanocomposites emerge as promising contenders for infection prevention in healthcare settings.

The impact of different concentrations of natural antioxidants (curcumin) on the thermal stability of UHMWPE (ultra-high molecular weight polyethylene) is examined via the thermogravimetric (TGA/DTA) technique, in the temperature region 50–600 °C at a 5 °C/min heating rate. This work employs the model fitting (Coats and Redfern) approach to determine the optimal curcumin concentration. UHMWPE samples at optimum concentration are further subjected to three other heating rates, viz., 10, 15 and 20 °C. A bi-Gaussian asymmetric function is utilized for deconvolution to elucidate the complexities of thermal decomposition. Through deconvolution, two peaks are obtained and the activation energy corresponding to each peak is determined through two iso-conversional kinetic (Friedman and Starink) models. By utilizing activation energy, the random nucleation reaction mechanism involved in thermal decomposition is recognized. Finally, changes in entropy (left(Delta Sright)), enthalpy (left(Delta Hright)) and Gibbs free energy (left(Delta Gright)) are determined.

This study investigates the effect of coating AP with RGO on its thermal decomposition kinetics and behavior. Differential scanning calorimetry (DSC) was performed for pure AP and AP@RGO at several heating rates. DSC curves of AP@RGO for various heating rates were split into individual reactions using a mathematical deconvolution approach. The assessment of kinetic triplets of various reactions was accomplished for both AP and AP@RGO using an effective model-free approach (MFA). Deconvolution of the DSC curve for AP@RGO reveals three distinct decomposition processes, compared to only two observed in pure AP. Notably, the low-temperature decomposition reaction appears to be catalyzed by RGO, leading to a dramatic decrease in activation energy from 164 to 116 kJ/g. Conversely, the high-temperature decomposition remains uncatalyzed, with a slight increase in activation energy from 177 to 188 kJ/g. The catalytic effectiveness of RGO in the thermal decomposition process of AP fluctuates due to structural transformations within RGO and its degradation in the presence of perchloric acid.